Needle-type lactate biosensor

A needle-type lactate biosensor has been developed for continuous intravasc ular lactate monitoring. The sensor employs poly(1,3-phenylenediamine) as t he inner layer on the platinum electrode in order to eliminate the interfer ence from oxidizable physiological substances. Cross-linking with glutarald ehyde was used for enzyme immobilization. Dithiothreitol was used as the st abilizer of lactate oxidase. PVC (polyvinyl chloride) was chosen as the ext ernal diffusion control membrane. Sensor performance was evaluated in vitro and the sensor shows a sensitivity of 10-15 nA/mM, and a linear range from 1 mM to at least 15 mM lactate. Evaluation of the sensor response in blood plasma showed similar sensitivity and linear range as indicated by the cal ibration curves obtained in buffer solution. The sensor has a short respons e time of approximately 1 minute. The sensors were operated continuously fo r 7 days in phosphate buffer containing solution with a concentration at th e physiological lactate level. No significant change in sensor sensitivity and its linear range has been observed. Sensors show a minimum change in it s performance when stored in buffer at 4 degrees C for at least 9 months. ( C) 1999 Elsevier Science S.A. All rights reserved.